Abstract:Fatigue property of cement-improved loess was studied with stress-controlled dynamic tri-axial tests to explore influences of cement content, confining pressure and consolidation ratio on its fatigue properties. The critical dynamic stress method and the dynamic shear strain method were adopted to evaluate the long-term dynamic stability of cement-improved loess subgrade. The results showed that the dynamic elastic modulus Ed of cement-improved loess has a trend of increasing firstly and then decreasing with increase in dynamic stress σd, the method to determine the fatigue dynamic shear strain threshold with Ed-σd curve is proposed; εp-lg N curves can be divided into stable type, critical one and destructive one according to their trends; With increase in cement content, confining pressure and consolidation ratio, the dynamic shear strain threshold and critical dynamic stress of cement-improved loess gradually increase, and cement content has the maximum influence on them, the influence of confining pressure is the second, the influence of consolidation ratio is the smallest; through the regression analysis, two simple and applicable empirical estimation formulas are obtained; when cement-improved loess is used as the subgrade bed bottom layer packing, the subgrade long-term dynamic stability can meet requirements; cement content is suggested to be controlled within about 5%; the dynamic shear strain method is a better evaluation method than the critical dynamic stress method be.
张沛云,马学宁,李善珍,王旭. 高速铁路水泥改良黄土路基长期动力稳定性评价[J]. 振动与冲击, 2019, 38(11): 80-87.
ZHANG Peiyun, MA Xuening, LI Shanzhen, WANG Xu . Long-term dynamic stability evaluation for cement-improved loess subgrade of high speed railway. JOURNAL OF VIBRATION AND SHOCK, 2019, 38(11): 80-87.
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